A rotary piston machine is described, for example, in DE 10 2007 001 021 A1. This comprises an annular channel, which is curved along an at least partial arc of a circle, and in which a piston can be caused to perform a movement along the arc by subjecting it to pressure with a fluid. This movement is transmitted by means of a lever connected to the piston to a rotary body, which has a rotational axis coaxial with the annular channel. Therefore, with the rotary piston machine a torque can be generated directly by hydraulic forces in contrast to a conventional hydraulic piston, which generates a linear force.
In the case of such a rotary piston machine the lever is configured as a substantially circular drive disc, which rotates around the rotational axis with the piston and the edge region of which is guided in an annular gap in the wall of the annular channel. According to principle, this annular gap must extend over the entire length of the arc, which should be available for a movement of the piston, i.e. in an extreme case along the entire periphery of a circle. This sets high demands on the necessary sealing of the annular channel against discharge of the hydraulic fluid between the walls of the annular channel and the lever. In this case, tightness must be assured both in the static state (stoppage of the piston and the lever) and in the dynamic state (movement of the piston and the lever) as well as at different pressures of the hydraulic fluid, which can typically be up to approximately 150 bar.
It is an object of the present invention to propose a sealing element for such a rotary piston machine, with which these demands can be met to a high degree.